My IP & IP Inspector

about this tool

Your address, from this site

The top panel is answered by this site's own server, not by an outside service. Every web host sees the address a request came from, and Cloudflare, which serves this site, attaches a country, a rough city, the network's name and its AS number to the request before it arrives. The page asks its own /api/ip endpoint for exactly that, with the answer marked uncacheable so no shared cache can hand your address to someone else.

That is a deliberate difference. The usual "what is my IP" page has your browser call a third-party lookup API, which gives that company a record of your visit. Here, nothing new leaves your machine: the information shown is what this site already had by virtue of serving you the page.

The location is a guess from a database, usually the nearest large city or the registered address of your provider, and mobile connections are often wrong by hundreds of miles. If the address shown is inside 100.64.0.0/10, your provider is sharing one public address between many customers.

Taking an address apart

The second panel reads any IPv4 or IPv6 address, entirely in the page, and tells you what it is. It refuses the ambiguous forms rather than guessing: an IPv4 part with a leading zero, because 010 is octal to some software and decimal to others, and an IPv6 address with two :: compressions, because there is then no way to know how many zero groups each stands for.

IPv6 is printed the one way RFC 5952 allows: lower case, no leading zeros, the longest run of zero groups compressed exactly once, the leftmost when two runs are the same length, and never a single group. The expanded form is shown too, along with the address as a decimal number and in hexadecimal, and the name a reverse lookup would ask for — 4.3.2.1.in-addr.arpa, or all thirty-two nibbles backwards under ip6.arpa.

The range an address belongs to comes from the IANA special-purpose registries: private networks, carrier-grade NAT, loopback, link-local, documentation ranges, multicast, unique local addresses, 6to4, NAT64 and the rest, each named with the document that set it aside. An IPv4 address hidden inside an IPv4-mapped, 6to4 or NAT64 address is pulled out and shown.

Limits

There is no geolocation of arbitrary addresses, no WHOIS and no reverse DNS lookup — the reverse name is constructed, not resolved, because resolving it would mean querying a DNS service from your browser. A VPN or proxy changes what the site sees, which is the point of one. Nothing here is logged or stored: the endpoint reads the request and answers it.

To look up records for a name rather than an address, use DNS lookup & subnet calculator. Your address is one of two things a server sees; the user-agent parser decodes the other.

questions

Where does my address come from?

From this site itself. Every web server sees the address a request came from, and Cloudflare, which hosts this site, attaches a rough location and network name to it before the request arrives. The page asks its own server for that and shows it. Most “what is my IP” pages send your browser to a third-party lookup service instead, which hands that service a visit it would not otherwise have had.

How exact is the location?

It is the city or region an address is registered to, which is often the nearest large city or the location of your provider rather than where you are. It is a guess from a database, not from your device, and mobile connections are frequently wrong by a long way.

Can I look up where someone else’s IP is?

Not here. Turning an arbitrary address into a place means sending it to a geolocation database, and this site does not make third-party requests. What you can do here is take any address apart: which range it belongs to, whether it is private, its canonical form, and the name a reverse lookup would ask for.

Why does it say my address is private or carrier-grade NAT?

Addresses in 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 only exist inside a local network, and 100.64.0.0/10 is what a provider uses when it shares one public address between many customers. If the address the site sees is one of those, something between you and the internet is doing the sharing.

Why does it refuse an address with a leading zero?

Because 010.1.1.1 means two different things depending on the software reading it: some treat a leading zero as octal, making it 8.1.1.1, and some read it as decimal. That ambiguity has been used to slip past address filters, so it is rejected rather than guessed at.